Lightweight valves of the kind referred to here are known (DE 19 804 053 A1). They are used inter alia as inlet and outlet valves for internal combustion engines and comprise a valve stem which is adjoined by a funnel/trumpet-shaped valve cone. For the purpose of weight reduction, the valve cone is hollow and has only a small wall thickness. The valve cone is closed at its end of greater diameter by means of a valve disk. According to one variant embodiment (figures four and five of DE 19 804 053 A1), the valve cone is formed by a separate sheet-metal component which is welded together with the valve stem and the valve cone. For this, the end of greater diameter of the valve cone is positioned with its end face opposite an annular surface located on that flat side of the valve disk facing the valve cone. Accurate alignment of valve cone and valve disk in relation to one another is extremely difficult owing to the only small bearing contact surfaces of these parts. Moreover, the weld seam formation possibilities in the regions of connection of the valve cone to the valve disk and the valve stem are limited.
As, in the lightweight valve mentioned above, the valve disk is not supported on a large area owing to the hollow space in the valve cone and the valve cone moreover has only a small wall thickness, the valve disk may be deformed during operation by the combustion pressure in the combustion chamber of the internal combustion engine, which contributes to premature wear of the lightweight valve. Furthermore, the thin-walled valve cone may also be deformed. In order to prevent this, DE 198 04 053 A1 proposes making the valve stem so long that it rests with its end face on that flat side of the valve disk facing away from the combustion chamber, by virtue of which the disk is supported. In this connection, the valve stem, which is hollow or made of solid material, and the valve disk can be welded together in their contact region. An alternative proposal is to manufacture the valve stem and the valve disk in one piece, that is as one part. In other alternatives, the valve disk is supported against the valve stem by means of an intermediate piece designed in one piece on the valve cone or a separate sleeve fixed between valve stem and valve disk. It is a disadvantage of the known lightweight valve that its individual parts can in some cases be produced only in a costly way owing to their geometry which is defined by the construction concerned and that accurate alignment of the individual parts in relation to one another before the joining process can be brought about only with high outlay.
A lightweight valve in which the hollow valve cone is formed on the valve stem end and in which means for supporting the valve cone and the valve disk are provided which are formed by reinforcing ribs arranged in the valve cone hollow space is disclosed by U.S. Pat. No. 2,439,240. The reinforcing ribs also improve the heat dissipation from the valve disk. The reinforcing ribs are designed in one piece on the valve disk or the valve cone or are alternatively inserted as a separate supporting framework into the valve cone hollow space.